As is well known, if a building is warm inside and cold outside, and there is sufficient humidity within the building, this humidity will condense on contact with the cold surface of the building. This is usually most noticeable at the roof. Such condensed humidity or moisture will eventually cause the wood and other roof material to rot. Thus preventative measures are typically necessary to prevent such condensation from occurring. One such measure is to adequately ventilate all parts of the building where condensation is likely to occur.
Apart from the condensation problem mentioned above, there also exists the basic ventilation problem of removing state air from enclosed spaces, and replacing it with fresh outside air. Roof mounted ventilation devices can also be used for this purpose.
Accordingly, there have been numerous examples proposed in the past of roof mounted structures to provide suitable ventilation for various ventilation purposes.
One such device is known as a Turbine Ventilator and is described in U.S. Pat. No. 3,267,833 to Artis et al. This invention provides a free flow roof turbine or ventilator, which have since become commonly utilized to inexpensively exhaust dormant hot air from attics or other space under a roofed area. They are also used to evacuate warm air from such areas as kitchens or laundries.
Turbine ventilators are generally constructed of a plurality of curvilinear blades supported in a freely rotatable frame. The blades are contoured and oriented in relation to one another such that warm air rising from below, passes through the blades and due to the blade orientation, urges the blades and consequently the frame to rotate and expel the warm air.
One of the disadvantages of the prior art turbine vent devices is that they require a minimum of two to four separate and distinct members or pieces which are relatively expensive to manufacture and which necessitate a relatively complicated process to construct together to form the desired vent apparatus. Moreover, such conventional turbine vent devices are not sturdy, have limited duration of use, are susceptible of deterioration when exposed to the elements, and require somewhat complicated interconnection procedures. Furthermore, the venting efficiency leaves room for improvement.
Another disadvantage of such turbine vent devices is that they do not provide adequate protection against insects and the weather (i.e. rain and snow) from entering through the device and into the vented area.
These problems with the turbine vent devices have been recognized and attempts have been made to address the various problems through the use of passive roof vents of various shapes, sizes, forms, and features.
However, all of these passive roof vents require the complete replacement of the turbine vent device including the exhaust shaft to which they are mounted, which adds to the expense of replacing these turbine vent devices.
Aside from the turbine roof vents, aging passive pot vents may have been installed begin to look unsightly or may be leaking, and may allow weather to pass through into the building enclosure.
Accordingly, what is desired is a cost effective way for replacing pre-existing turbine roof vent installations, while at the same time overcoming the problems with prior art roof vents. Furthermore, it is also desirable to overcome the problems associated with aging pot vents.